Digimon 5D's - Dark Chaos
by RaisingHeartExelion
Summary: A crossover to celebrate the fifth year anniversary of my "Crimson Star Priestess" fanfic, featuring my YGO 5D's OC, Estelle. The group is having a picnic when New Domino City gets invaded by rogue Digimon. Just before their mission is complete, Yusei meets an old friend who disappeared six months prior, but he has come back changed and with a Digimon. Cover by Omnimon1996 on DA.


**Hello and welcome to this crossover of Yu-Gi-Oh! 5D's and Digimon! This is a one-shot to celebrate the fifth year anniversary of my "Crimson Star Priestess" fanfic, so my OC, Estelle, is going to be added as one of the Chosen DigiDestineds/Tamers. This was voted on the poll I had on my profile to let the CSP fans choose what kind of fanfic I should write to celebrate the fifth year of me working on the main story.**

**I was working on another version of this crossover, but I had a feeling it would end up in multi-chapters, so I decided to stay with a one-shot and, maybe, work on the longer part in the near future.**

**The story is inspired by "Digimon Savers/Digimon Data Squad". In this realm, Duel Monsters don't exist.**

**All characters are around two years older than in the last part of the YGO 5D's anime (before their future selves), so Estelle is 24 years old in this one-shot.**

**The one-shot begins in Estelle's point of view.**

**Disclaimer:** I do not own any Yu-Gi-Oh! 5D's or Digimon characters! I only own my OCs!

**XXXXXXXXXX**

It was a calm and beautiful spring day in New Domino City today. It was the perfect weather to be outside and play some games or go on picnics with the loved ones. The right corner of my lips twitched a bit when I thought about of how my friends and I were kinda limited to our activities due to our secret.

I grabbed the handles of my crimson motorcycle and drove as the traffic light turned green for me. I was heading to the base to meet up with my friends to spend some time in the private cherry tree garden to celebrate the spring with a hanami.

I made it to the base in five minutes and removed my gear before grabbing the basket I had tied on the motorcycle behind me and headed inside the building that was known as Sector Security, but it had a different section where my friends and I worked at.

I walked through the long corridors before I found my way to the garden that was located in the middle of the property. The scent of blooming cherry trees invaded my nose and I inhaled deeply to enjoy the sweet aroma.

"Estelle!" a young girl's voice called.

I turned my head and found my friends waiting for me to join the hanami in the middle of the garden, next to a small artificial riverbank. Their Digimon partners were outside of the Digivices, enjoying the freedom and the food we had all prepared.

"Hi, guys", I smiled softly as I joined them. "Sorry you had to wait for me."

"Nah, you're not late, gal", Crow grinned bright as his partner, Falcomon, munched on a salad sandwich. "We're the ones who're here early."

Hackmon, Jack's partner, walked over to me. "Is Dorumon with you?"

"Of course he is", I smiled with a nod before picking up my lilac Digivice iC. "Dorumon: Realize!"

Lilac digital particles shot out from the Digivice and formed my partner, Dorumon. He stretched his body a bit before turning to the orange dinosaur Digimon. "Hi, Hackmon. Hi, everyone."

"Hi!" Lalamon, Akiza's Digimon, waved her short hand while floating next to the burgundy-haired girl.

Luna and Yusei moved a bit on the huge blanket everyone sat on, so Dorumon and I could sit down and join the picnic. I packed up some finger food that was traditional in my home country, Sweden; homemade meatballs and meatball sandwiches, egg sandwiches made by crispbread, cheese cubes and some fresh salad with toothpicks, and a thermos of my favorite tea.

"Yum! That looks so delicious!" Leo commented with shiny eyes while drooling at the sight of the food. "Can I try one?"

"Be my guest", I responded.

Leo immediately snatched one sandwich of each kind and tried eating both of them at the same time. Terriermon, his partner, used his long ears to grab an egg sandwich and munched on it calmly compared to the mess the male twin was making.

"Leo, slow down a bit! You're gonna choke!" Luna scolded him as her Digimon, Lopmon, ate a rice ball while sitting on her Tamer's lap.

"I'm glad you've got better manners, Brother", the brown/pink mammal Digimon told her twin brother.

"Well… I'll get scolded too if I make a mess, Sister", Terriermon replied.

I picked up a few paper mugs from the basket and poured tea in two of them, one for me and one for Dorumon. "Does someone want some Earl Grey tea?"

"I'd like to try it", Yusei said before turning to Gaomon. "What about you, Gaomon?"

"I'd like a cup of the tea too, thank you", Gaomon nodded.

"Okay", I said before pouring tea in two more mugs and gave them to Yusei. "Here you are."

"Thanks", Yusei nodded before he took both mugs. His fingers touched mine for a second and I felt a ting of spark by the contact. I blushed slightly and turned my head away to make sure he didn't see my pink cheeks.

Yusei handed one of the mugs to Gaomon who held it with both his paws that were covered by a pair of red boxing gloves. "Here, buddy."

"Thank you, sir", Gaomon nodded politely.

Yusei laughed a bit sheepishly. "I'll never get used to being called 'sir'."

"It just shows how loyal Gaomon is to you", Akiza spoke up before taking a bite of an omelet roll.

"Just like a real dog", Jack snorted as he sipped his coffee in another paper mug.

"Say… What kind of games should we play after eating?" Luna wondered.

"I'm up for badminton", Falcomon said.

"Or a simple game of tag", Hackmon suggested with a soft laugh.

"Well, the garden is not that wide, so a game of tag won't do", Dorumon said.

"I've brought some soap bubbles with me, if case someone just wants to blow bubbles", I spoke up.

"That's too childish!" Jack snorted with his nose held up high. "Blowing bubbles is just for kids!"

"Hey, I enjoy blowing bubbles even as an adult", I argued softly.

"Yeah, so do I!" Crow raised his hand. "I often blow bubbles with my little brother, Yoshi, in the garden at home."

"How about collecting fallen cherry flowers?" Akiza suggested. "The one who found most complete flowers within a limited time wins?"

"I'm for it!" Lalamon voted.

"Nah, that's for girls!" Leo waved his hand nonchalantely. "I'm out!"

"Sounds like badminton will be the winner", Falcomon laughed softly.

"I guess so, unless sir comes up with an idea too", Gaomon nodded.

Yusei thought deeply before opening his mouth. "How about we go with-"

"Everyone!"

We looked up from our conversation and turned around to see Mina running towards us. Her face told me it was full of panic and that meant something was wrong.

"Mina? Is something wrong?" I asked as I stood up from the blanket.

Mina rested her hands on her knees when she reached us, but her face was still pale. "T-There's…an emergency… Goodwin…needs you now!"

**XXXXXXXXXX**

Our hanami picnic came to a halt when we were ordered to hurry to the main control room of the Digimon section. We all swiftly changed into our uniforms before heading to the control room for the emergency. I was dressed in a dark lavender suit that reached to my mid-thighs, a lavender/white jacket, white belt around my waist, and a pair of white boots. Akiza and Luna were dressed in the same uniform as me, but Akiza's suit was rose red with a magenta/white jacket, and Luna's were dark pink and pink.

The young men's suits were longer that reached down to their ankles, and they had the same jacket as us girls, but their boots were shorter and the edges had a different color. Yusei's suit was navy blue while the jacket was blue/white and the edge of his boots was blue as well. Jack's suit was completely white while his jacket was white and purple, and his white boots had a purple edge. Crow's suit was black with a dark orange/black jacket and his boots were black with orange edges. Leo's suit was dark green with a green/white jacket and his white boots had forest green edges.

Goodwin was already waiting for us as we entered the control room, only to get shocking news. The surveillance footage showed us a giant horde of Digimon invading the streets of New Domino City. The majority of the rogue Digimon were virus attributed, but there were a few that were vaccine too. The Digimon were attacking the citizens, showing no mercy as they attacked children and adults like.

"Are you kidding me?!" Crow exclaimed in disbelief. "On all days, these Digimon had to show up on our free day?!"

"We need to move out and fast before there are more casualties!" Akiza called.

"I agree!" I nodded before turning to the Director. "Goodwin!"

Goodwin nodded, "Everyone, move out! Protect our city!"

**XXXXXXXXXX**

It was pure chaos when we reached the downtown with our digivolved Digimon. I sat on DoruGreymon's back as we flew above the horde that attacked the people and destroyed buildings left and right. Akiza sat behind me as Lilamon flew next to us. "What should we do?" the young adult asked behind me.

"_We need to split up!_" Yusei's voice called from my earpiece as he and MachGaogamon was in a different part of the city. "_The aerial Digimon should focus on the aerial troops while the rest of us take care of the ground Digimon!_"

"_Leo and I'll do our best to evacuate everyone while Gargomon and Turuiemon cover us!_" Luna called.

"_Crowmon and I'll be part of the aerial team!_" Crow chimed in. "_Our strength is, after all, in the air!_"

"There's no time for puns, Crow!" Akiza growled. "Estelle, what do we do?"

"Jack, what's your position?" I asked.

"_SaviorHuckmon and I are both in the aerial and the ground!_" Jack responded. "_We can take care of every Digimon that comes in our path!_"

"Don't hesitate to call for backup!" I told him before turning to Akiza. "DoruGreymon will take care of the Digimon at the ground and Lilamon in the sky! We'll jump in whenever we see if one needs help!"

Akiza nodded and turned to her partner. "You heard her, Lilamon?"

"Yes, Aki!" Lilamon nodded. "Ready, DoruGreymon?"

"Let's protect our home!" DoruGreymon roared before he flew down to the ground.

Lilamon flew towards the aerial horde of Digimon. "**Marvel Shot**!"

"**Metal Meteor**!"

The attacks hit one Digimon after another, turning them all into Digi-Egg as they were slowly defeated. The streets were turning empty as there were less Digimon. Whenever we spotted humans, whether they were injured or not, we told them to hurry to the shelters while we requested medical attention from HQ.

Everything seemed to go well, until Goodwin's voice spoke up from the earpieces.

"_Attention, all teams! Our computer operators have spotted the signal of a Mega Digimon nearby! Regroup and defeat the Digimon as quickly as you can! We're getting readings that are off charts and very concerning!_"

"Yes, sir!" we all called.

"That didn't sound good", Akiza commented nervously.

"A Mega Digimon is stronger than any Ultimate Digimon", DoruGreymon explained. "But we might have a chance to defeat it since we are five Ultimate!"

"The streets nearby are empty, so we can leave!" Lilamon called as she returned after a quick scouting.

"Alright! Let's go!" I said.

DoruGreymon and Lilamon flew away from the streets to reach the area where we were supposed to regroup. However, a few minutes later, my earpiece started beeping so I turned it on.

"_Guys, the Mega Digimon is right in front of me and MachGaogamon!_" Yusei informed us.

"What?!" we all exclaimed in shock and disbelief.

"_And Kalin is with-_", Yusei continued before I heard a loud thud in the background. "_MachGaogamon, no! Guys, hurry up!_"

"_We're coming, Yusei! Just hold on!_" Crow shouted.

"_Wait, Yusei, did you just say-_", Jack began before the connection with Yusei got cut.

"_Yusei? Yusei?! Can you hear us?!_" Leo's frantic voice called.

"He must've been attacked too!" Akiza exclaimed in shock.

"_But what was that with Kalin?!_" Jack questioned. "_He's been missing for more than six months! Don't tell me he's the one behind the invasion?!_"

"_That's impossible! He's our friend, but he never had a Digimon by his side!_" Crow added.

I was getting a bad feeling about this. "Everyone, forget about regrouping and hurry to Yusei's location! Something feels wrong here!"

"_I'm with you, Estelle!_" Luna agreed. "_I feel something dark and it's making me sick…_"

"_Hang on, Luna! I got you!_" Leo said.

"_Perhaps you should stay behind, twins!_" Crow suggested.

"_NO!_" the twins yelled simultaneously.

"_I can still go!_" Luna insisted.

"_Yeah, and where Luna's going, I'm going too!_" Leo added.

"Alright then, but stay in the background!" I told them. "We don't know who the enemy is!"

Hang on, Yusei… We're coming!

**XXXXXXXXXX – Yusei's POV**

"**Winning Knuckle**!"

MachGaogamon released a tornado with his fist and cleared the entire street of the rogue Digimon. They all turned simultaneously into a sea of Digi-Eggs, ready to be transported to HQ.

"That should be the last of them in this area, sir", MachGaogamon said.

I picked up my mini-laptop and checked the entire city for other energy signatures. I could also see my friends' Digivices and their Digimon's signatures on the screen as they took out the rogue Digimon in the other areas.

"It looks like the others are doing well too", I nodded. "All wild Digimon has almost turned back into Digi-Eggs."

"What's your next order, sir?"

"Let's go and see if the twins are doing", I told him as I put away the laptop. "They were, after all, ordered to evacuate the people to the shelters. Their Digimon are only in Champion level, so they might need help."

"Understood, sir."

MachGaogamon was about to lower his hand to pick me up when a voice broke the silence.

"Leaving already, Yusei?"

The familiar voice sounded so dark and cold that I felt a cold run down my spine. I turned around and saw the figure of Kalin walk out of an alley. I hadn't seen or heard from him since he disappeared six months ago.

"Kalin?!" I gasped in disbelief. "What are you doing here?"

Something felt off with my old friend. His eyes were dark and evil; I had never seen them before. He used to be a warm person, but now he was different. Even his clothes were black with red highlights.

"What am I doing here, you ask?" Kalin laughed. "I'm here to destroy the world for my master!"

"Master…?" I mumbled confusedly before my eyes widened in realization. "Kalin, are you under someone's control?!"

"I'm under no one's control!" Kalin laughed before he raised his hand to the sky. "But let's meet my new friend!"

A Digi Gate opened in the sky before a huge Digimon descended from it. MachGaogamon and I watched in horror as the Digimon landed on the street, blocking down a few buildings to the side due to its size. It was twice as big as MachGaogamon, but it was a red dinosaur Digimon with red futuristic wings.

"What is that?!" I exclaimed while I noticed the Mega Digimon's eyes seemed hollow, as if it wasn't under control of its own body.

"This is my partner, ShineGreymon!" Kalin laughed before he revealed a black Digivice in his left hand, but it looked like an upgrade version of the iC. "And I've got more surprises!" His right hand began sparkling by a nasty dark red and black digital particle aura before he put his hand on top of the Digivice.

"Kalin, stop!" I yelled.

"D.N.A. CHARGE: BURST MODE!"

ShineGreymon was enveloped by Kalin's D.N.A. Charge as his appearance slowly changed. However, I noticed how the Mega Digimon seemed to be in pain as he roared while clutching his head with both hands. His wings began burning with a black fire as his armor changed from red and white to crimson, black and grey. His eyes glowed in red as he allowed the dark D.N.A. Charge take over him.

"ShineGreymon Ruin Mode!"

I stared at ShineGreymon in disbelief. I've heard about side evolutions for certain Digimon, but this was the first time I've witnessed a Mega Digimon having a side evolution. I had to inform my friends!

"Guys, the Mega Digimon is right in front of me and MachGaogamon!" I told them through the earpiece.

"_What?!_" we all exclaimed in shock and disbelief.

"And Kalin is with-", I was about to tell them more when MachGaogamon was punched hard by ShineGreymon, crashing into a building. "MachGaogamon, no! Guys, hurry up!"

"_We're coming, Yusei! Just hold on!_" Crow shouted.

The next thing I knew, Kalin punched me in the face. I fell down on the ground, grunting a bit by the pain before my former friend grabbed me by the collar and picked me up. His dark eyes stared deeply into mine as his vicious grin grew on his lips.

"No more of that, Yusei", Kalin grinned before he snatched my earpiece from my ear and crushed it in his fist.

I didn't want to do this, but I punched Kalin in his cheek, causing him to let go of me. I fell down on my backside, but I quickly jumped up on my feet and backed away from him.

"What happened to you, Kalin?" I asked. "Why would you cause harm to people? That's not like you!"

"What happened to me? My master showed me the truth of the world!" Kalin replied after he recovered from the punch. "In order for Digimon to live in the Digital World, we need to delete the current Digital World to create a new and peaceful one with no enemies!"

"What?! What's that about?!" I asked.

"S-Sir…", MachGaogamon grunted as he raised up on his feet weakly.

"MachGaogamon?" I said as I turned to my partner.

"ShineGreymon, destroy the mutt!" Kalin commanded.

ShineGreymon growled as I could hear his wings powering up like a machine. "**Shining Blast**!"

He mowed down MachGaogamon with his wings of glimmering light. MachGaogamon cried in pain as he was enveloped by the dark light.

"MACHGAOGAMON!" I yelled in horror.

As soon as the light died down, MachGaogamon was nowhere to be seen, because he was in his In-Training form, Wanyamon.

"Wanyamon!" I called as I rushed to my defeated partner.

Wanyamon grunted in pain as I carefully picked him up in my arms, holding him close to my chest. "I… I'm sorry, sir…"

"It's okay, Wanyamon", I told him calmly. "You did your best."

"Sir… A-About ShineGreymon…", Wanyamon grunted as his big hazel eyes looked at me.

"Well, looks like we should destroy you two together", Kalin laughed.

"Not so fast, Kalin!" Crow's voice echoed from the sky.

I looked up and saw Crowmon's figure descending to the ground while blocking the sun. SaviorHuckmon, DoruGreymon, Lilamon, Gargomon, and Turuiemon followed him as they got down to the ground. My friends jumped off their Digimon partners and joined me as they had their attention on Kalin.

"Bro, what is wrong with you?!" Crow yelled at him. "You disappear for six months and now you show up, just to be a bad guy?!"

"Me, the bad guy?" Kalin laughed maliciously. "I should say that to you guys, because you destroyed so many innocent Digimon!"

"Innocent Digimon?! They were invading our city and hurt people and destroyed buildings left to right!" Leo argued.

"Besides, they weren't destroyed; they were just turned back into Digi-Eggs", Akiza added.

I noticed how Luna hid behind Estelle while her eyes were on ShineGreymon. She always had this mysterious ability to sense dark aura, so she was probably feeling lots of it coming both from the Mega Digimon and Kalin.

"Pah! Keep coming up with all those excuses! ShineGreymon will destroy all of you, so all Digimon can migrate to the Real World and wait for the Digital World to be reborn for a better life!"

"What are you talking about, Kalin?" Estelle questioned worriedly.

"No time for questions, Estelle! We've gotta take down ShineGreymon!" Jack said as he grabbed his white and amethyst-purple Digivice. "We're the only ones who can digivolve our Digimon to their Mega forms!"

"Yeah…", Estelle nodded as she hesitantly reached for her Digivice strapped into her belt.

"Wait!" I called, getting their attention. "That ShineGreymon is in a side evolution called 'Ruin Mode'. He easily defeated MachGaogamon and forced him into his In-Training form with just one attack."

"Even so, we can't give up!" Jack spat, frustrated. "Our city is in danger because of that monstrosity and we need to get rid of it!"

"And arrest Kalin if he knows more than he speaks of", Estelle added as her worried expression had switched into determination.

DoruGreymon and SaviorHuckmon returned into their Rookie forms for the next evolution. Jack and Estelle looked at each other and nodded before both their bodies were enveloped in white respective lilac aura and they slammed their hands on top of their Digivices.

"D.N.A. Charge: Overdrive!"

"Dorumon warp digivolve to…Dorugoramon!"

"Hackmon warp digivolve to…Jesmon!"

The two Mega Digimon stood in front of us as they glared at ShineGreymon. The other Digimon joined them as they were ready to attack at command.

Kalin snorted loudly. "Two Mega Digimon; one of them being a Royal Knight. Two Ultimate and two Champion Digimon. No matter, ShineGreymon is stronger with the power of dark D.N.A.!"

"Wanna bet, you moron?!" Crow yelled, frustrated.

"Who are you working for, Kalin?" I asked. "Who is your master?"

I had to get some more information out of him. That way, maybe we could find the pieces of the puzzle of this invasion and this talk about creating a new Digital World.

"Would you like to know?" Kalin laughed before he grew stiff, which we all noticed.

"What happened to him just now?" Akiza questioned.

Luna whimpered in fear as she stood close to me. "Luna, what's wrong?" her twin brother asked worriedly.

"I-I sense…a dark and very powerful aura coming from Kalin…", she replied with a shaking voice.

"I believe his master is communicating with him through telepathy", Jesmon spoke up with a deep and echoing voice.

"Yes, because none of us Digimon can't sense an incoming dark aura", Dorugoramon nodded.

Kalin growled softly through gritted teeth. "It looks like my master is telling me to return to the Digital World, since this mission is already meant to be a failure. I'd love to stay and watch you burn into ashes, but I must follow Master's orders."

"You coward!" Jack growled.

Kalin laughed, "Says the one who didn't order your Digimon to attack ShineGreymon as soon as you digivolved them."

Another Digi Gate opened in the sky as ShineGreymon lowered one of his hands to the ground to pick up Kalin. He made himself comfortable on the palm as his Digimon flew up to the sky.

"Wait! Come back, Kalin!" Crow called.

"See you later, old friends!" Kalin laughed as ShineGreymon flew into the Digi Gate.

We watched how the Digi Gate closed and vanished in the sky, leaving no trace behind. We all stood there silently in the ruined streets while the other Digimon returned into their Rookie forms.

"What the heck was all of this about…?" Leo questioned. "The Digital World being reborn…?"

"And Kalin is working for someone who wants to destroy that world…?" Akiza added.

Lopmon jumped into Luna's arms and wrapped her ears around the girl to give her comfort. "It's okay, Luna… They're gone now."

"Could Kalin's new behavior have something to do with his disappearance?" Estelle wondered.

"That could be it", I nodded while still feeling shocked to see one of my best friends turning against us. "Someone is controlling him, making him unable to think rationally."

"Whoever is controlling him is requesting a big beating from us", Jack growled before cracking his knuckles.

"Yeah, we need to save him _and_ the Digital World!" Crow nodded.

I nodded in agreement. "But before that, we need to return to HQ for us to rest while the other teams take care of the Digi-Eggs."

"Yeah, I'm exhausted", Lalamon sighed as she tried wiping her forehead.

"But we all did our best and lowered the number of causalities", Dorumon nodded.

We walked away from the street, but I stayed behind to look at the sky where I last saw Kalin. What happened to him? He used to be a big brother figure to me, so for him to switch page and become an evil person…

"Yusei?" Estelle called softly.

I turned around to see she looked concerned, knowing how much this encounter had hurt me. "Estelle…"

"Don't worry; we'll somehow bring Kalin back to his senses", the brunette told me with a small smile.

"I hope so…", I mumbled before I glanced at Wanyamon who had fallen asleep in my arms. "But that dark aura… It's so powerful. I don't know if we can really defeat him."

"We can and we will", Estelle assured me before placing a hand on my left shoulder, making me look up at her. "You have to believe in yourself, Wanyamon, and the rest of us. You're not alone because we will always fight together as a team."

She was right. I wasn't alone. We could, hopefully, get Kalin back and at the same time destroy his master and save both the Digital World and the Real World, but before that, I had to get much stronger to digivolve my partner to his Mega form. Only then I could rescue my friend.


End file.
